Frost Dates for Harwood Heights, IL 60706
Last spring frost April 25 · First fall frost October 13 · 171 frost-free days · USDA Zone 6a
ZIP 60706 has about 24,300 people.
Moderate season: 171 frost-free days. Spring frost risk spans April 10–May 10 (30 days). Fall frost risk spans September 28–October 28 (30 days).
Frost probability for 60706
| Frost | 10% | 50% | 90% |
|---|---|---|---|
| Spring (last frost) | May 10 | April 25 | April 10 |
| Fall (first frost) | September 28 | October 13 | October 28 |
Dates come from NOAA 1971–2000 freeze probabilities at CHICAGO O'HARE AP (9.5 km away); the 50% date is the median year.
Which crops fit a 171-day season in Harwood Heights
In Harwood Heights (171 frost-free days, a moderate season), 30 of 56 planner crops fit outright, 25 get two plantings, 1 crop is perennial.
| Crop | Start indoors | Plant out / sow | Days you have | Verdict | Last sow date |
|---|---|---|---|---|---|
| Tomato | Mar 21 | May 9–May 16 | 129 | fits: 80 days to maturity, 129 available after May 9. | Jun 13 |
| Pepper | Mar 14 | May 9–May 16 | 129 | fits: 75 days to maturity, 129 available after May 9. | Jun 18 |
| Lettuce | Feb 28 | Mar 28–Apr 4 | 206 | two-plantings: Plant Mar 28 and again by Aug 22; both mature before Oct 20. | Aug 22 |
| Carrots | — | Apr 4–Apr 11 | 213 | fits: 70 days to maturity, 213 available after Apr 4. | Aug 11 |
| Cucumber | Apr 4 | May 9–May 16 | 143 | two-plantings: Plant May 9 and again by Jul 17; both mature before Sep 29. | Jul 17 |
| Beans | — | May 2–May 16 | 157 | two-plantings: Plant May 2 and again by Jul 24; both mature before Oct 6. | Jul 24 |
| Peas | — | Feb 28–May 9 | 234 | fits: 65 days to maturity, 234 available after Feb 28. | Aug 2 |
| Zucchini | Apr 11 | May 9–May 16 | 143 | two-plantings: Plant May 9 and again by Jul 22; both mature before Sep 29. | Jul 22 |
| Onion | Jan 31 | Mar 28–Apr 11 | 206 | fits: 100 days to maturity, 206 available after Mar 28. | — |
| Spinach | — | Feb 28–Apr 18 | 248 | two-plantings: Plant Feb 28 and again by Sep 10; both mature before Nov 3. | Sep 10 |
| Kale | Feb 14 | Mar 28–Apr 11 | 220 | two-plantings: Plant Mar 28 and again by Aug 26; both mature before Nov 3. | Aug 26 |
| Broccoli | Feb 28 | Mar 28–Apr 11 | 206 | fits: 80 days to maturity, 206 available after Mar 28. | Jul 18 |
| Cabbage | Feb 28 | Mar 28–Apr 11 | 220 | fits: 70 days to maturity, 220 available after Mar 28. | Aug 11 |
| Radish | — | Feb 28–May 23 | 234 | two-plantings: Plant Feb 28 and again by Sep 11; both mature before Oct 20. | Sep 11 |
| Beets | — | Feb 28–May 23 | 234 | two-plantings: Plant Feb 28 and again by Aug 12; both mature before Oct 20. | Aug 12 |
| Potatoes | — | Apr 11–Apr 18 | 192 | fits: 90 days to maturity, 192 available after Apr 11. | — |
| Garlic | — | Oct 13 | 276 | overwinter: Plant Oct 13 to Nov 3; harvest the following summer. | Nov 3 |
| Strawberry | — | Mar 21–May 16 | 227 | perennial: A perennial: plant Mar 21; it fruits from the following year and keeps producing for several years. | — |
| Corn | Mar 28 | May 2–May 9 | 143 | fits: 75 days to maturity, 143 available after May 2. | Jun 25 |
| Pumpkin | Apr 11 | May 9–May 9 | 136 | fits: 100 days to maturity, 136 available after May 9. | May 31 |
| Cauliflower | Mar 14 | Apr 18–May 2 | 185 | fits: 75 days to maturity, 185 available after Apr 18. | Jul 23 |
| Swiss Chard | Feb 28 | Apr 11–Apr 11 | 192 | two-plantings: Plant Apr 11 and again by Aug 12; both mature before Oct 20. | Aug 12 |
| Arugula | — | Feb 28–May 23 | 248 | two-plantings: Plant Feb 28 and again by Sep 10; both mature before Nov 3. | Sep 10 |
| Brussel Sprouts | Feb 28 | Mar 28–Apr 11 | 220 | fits: 100 days to maturity, 220 available after Mar 28. | Jul 12 |
| Butternut Squash | Apr 11 | May 9–May 16 | 136 | fits: 100 days to maturity, 136 available after May 9. | May 31 |
| Eggplant | Mar 7 | May 9–May 16 | 129 | fits: 70 days to maturity, 129 available after May 9. | Jun 23 |
| Okra | Mar 28 | May 2–May 9 | 150 | two-plantings: Plant May 2 and again by Jul 22; both mature before Sep 29. | Jul 22 |
| Basil | Mar 21 | May 16–May 16 | 136 | two-plantings: Plant May 16 and again by Jul 17; both mature before Sep 29. | Jul 17 |
| Cilantro | — | Mar 28–Apr 18 | 206 | two-plantings: Plant Mar 28 and again by Aug 17; both mature before Oct 20. | Aug 17 |
| Parsley | Feb 14 | May 2–May 9 | 171 | fits: 70 days to maturity, 171 available after May 2. | Jul 28 |
| Celery | Feb 14 | May 2–May 16 | 171 | fits: 120 days to maturity, 171 available after May 2. | Jun 8 |
| Scallions | Feb 14 | Mar 28–Apr 11 | 220 | two-plantings: Plant Mar 28 and again by Aug 21; both mature before Nov 3. | Aug 21 |
| Turnip | — | Mar 28–Apr 11 | 220 | two-plantings: Plant Mar 28 and again by Aug 31; both mature before Nov 3. | Aug 31 |
| Kohlrabi | — | Mar 14–Mar 28 | 234 | two-plantings: Plant Mar 14 and again by Aug 26; both mature before Nov 3. | Aug 26 |
| Bok Choy | Mar 28 | Apr 18–Apr 25 | 185 | two-plantings: Plant Apr 18 and again by Aug 22; both mature before Oct 20. | Aug 22 |
| Collards | Feb 14 | Mar 28–Apr 11 | 220 | two-plantings: Plant Mar 28 and again by Aug 21; both mature before Nov 3. | Aug 21 |
| Cantaloupe | Apr 11 | May 9–May 16 | 129 | fits: 85 days to maturity, 129 available after May 9. | Jun 8 |
| Chives | Jan 31 | May 2–May 9 | 185 | fits: 90 days to maturity, 185 available after May 2. | — |
| Dill | — | Feb 28–May 23 | 234 | two-plantings: Plant Feb 28 and again by Aug 12; both mature before Oct 20. | Aug 12 |
| Oregano | Feb 14 | May 2–May 9 | 185 | fits: 80 days to maturity, 185 available after May 2. | — |
| Rosemary | Jan 31 | May 2–May 9 | 171 | fits: 80 days to maturity, 171 available after May 2. | — |
| Sage | Feb 28 | May 2–May 9 | 185 | fits: 75 days to maturity, 185 available after May 2. | — |
| Thyme | Feb 14 | May 2–May 9 | 185 | fits: 90 days to maturity, 185 available after May 2. | — |
| Calendula | Mar 14 | Apr 11–Apr 25 | 192 | two-plantings: Plant Apr 11 and again by Aug 17; both mature before Oct 20. | Aug 17 |
| Cosmos | Mar 28 | Apr 25–May 9 | 157 | two-plantings: Plant Apr 25 and again by Jul 17; both mature before Sep 29. | Jul 17 |
| Lavender | Jan 31 | Apr 25–May 9 | 192 | fits: 90 days to maturity, 192 available after Apr 25. | — |
| Marigolds | Mar 14 | Apr 25–May 2 | 157 | two-plantings: Plant Apr 25 and again by Jul 27; both mature before Sep 29. | Jul 27 |
| Melons | Apr 11 | May 9–May 16 | 129 | fits: 85 days to maturity, 129 available after May 9. | Jun 8 |
| Mint | — | Apr 25–May 9 | 192 | fits: 90 days to maturity, 192 available after Apr 25. | — |
| Nasturtiums | Mar 28 | Apr 25–May 2 | 157 | two-plantings: Plant Apr 25 and again by Jul 22; both mature before Sep 29. | Jul 22 |
| Pole Beans | — | May 2–May 16 | 150 | fits: 65 days to maturity, 150 available after May 2. | Jul 12 |
| Spaghetti Squash | Apr 11 | May 9–May 16 | 136 | fits: 90 days to maturity, 136 available after May 9. | Jun 10 |
| Sunflowers | — | Apr 25–May 9 | 157 | fits: 70 days to maturity, 157 available after Apr 25. | Jul 7 |
| Tomatillos | Feb 28 | May 2–May 9 | 136 | fits: 75 days to maturity, 136 available after May 2. | Jun 18 |
| Watermelon | Apr 11 | May 2–May 9 | 136 | fits: 80 days to maturity, 136 available after May 2. | Jun 13 |
| Yellow Squash | Apr 11 | May 9–May 16 | 143 | two-plantings: Plant May 9 and again by Jul 22; both mature before Sep 29. | Jul 22 |
| Zinnias | Mar 28 | Apr 25–May 9 | 157 | two-plantings: Plant Apr 25 and again by Jul 17; both mature before Sep 29. | Jul 17 |
Month by month in Harwood Heights
| Month | What to do |
|---|---|
| January | Start indoors: Chives (Jan 31), Lavender (Jan 31), Onion (Jan 31), Rosemary (Jan 31). |
| February | Start indoors: Celery (Feb 14), Collards (Feb 14), Kale (Feb 14), Oregano (Feb 14), Parsley (Feb 14), Scallions (Feb 14), +8 more. Direct sow from: Arugula (Feb 28), Beets (Feb 28), Dill (Feb 28), Peas (Feb 28), Radish (Feb 28), Spinach (Feb 28). |
| March | Start indoors: Eggplant (Mar 7), Calendula (Mar 14), Cauliflower (Mar 14), Marigolds (Mar 14), Pepper (Mar 14), Basil (Mar 21), +7 more. Direct sow from: Kohlrabi (Mar 14), Cilantro (Mar 28), Turnip (Mar 28). Transplant from: Broccoli (Mar 28), Brussel Sprouts (Mar 28), Cabbage (Mar 28), Collards (Mar 28), Kale (Mar 28), Lettuce (Mar 28), +2 more. Plant: Strawberry (Mar 21). |
| April | Start indoors: Cucumber (Apr 4), Butternut Squash (Apr 11), Cantaloupe (Apr 11), Melons (Apr 11), Pumpkin (Apr 11), Spaghetti Squash (Apr 11), +3 more. Direct sow from: Carrots (Apr 4), Potatoes (Apr 11), Sunflowers (Apr 25). Transplant from: Calendula (Apr 11), Swiss Chard (Apr 11), Bok Choy (Apr 18), Cauliflower (Apr 18), Cosmos (Apr 25), Lavender (Apr 25), +4 more. Last frost around April 25. |
| May | Direct sow from: Beans (May 2), Pole Beans (May 2). Transplant from: Celery (May 2), Chives (May 2), Corn (May 2), Okra (May 2), Oregano (May 2), Parsley (May 2), +17 more. Last sowing dates: Butternut Squash (May 31), Pumpkin (May 31). |
| June | Last sowing dates: Cantaloupe (Jun 8), Celery (Jun 8), Melons (Jun 8), Spaghetti Squash (Jun 10), Tomato (Jun 13), Watermelon (Jun 13), +4 more. |
| July | Last sowing dates: Sunflowers (Jul 7), Brussel Sprouts (Jul 12), Pole Beans (Jul 12), Basil (Jul 17), Cosmos (Jul 17), Cucumber (Jul 17), +10 more. |
| August | Last sowing dates: Peas (Aug 2), Cabbage (Aug 11), Carrots (Aug 11), Beets (Aug 12), Dill (Aug 12), Swiss Chard (Aug 12), +9 more. |
| September | Last sowing dates: Arugula (Sep 10), Spinach (Sep 10), Radish (Sep 11). |
| October | Direct sow from: Garlic (Oct 13). First frost around October 13. |
| November | Last sowing dates: Garlic (Nov 3). |
| December | Clean up spent plants. Add compost to beds. Rest, review, and plan next year's garden. |
Frequently Asked Questions
What is the last frost date for Harwood Heights, IL (ZIP 60706)?
The median last spring frost date for Harwood Heights, IL (ZIP code 60706) is around April 25. This is the 50th-percentile date — meaning half of all years see frost end before this date. Use the 10% and 90% dates to understand the full range of risk in your area. One year in ten frost ends before April 10; one in ten it runs past May 10.
What is the first fall frost date in Harwood Heights, IL?
The median first fall frost date for Harwood Heights, IL is around October 13. Plan to harvest or protect frost-sensitive crops like tomatoes and peppers at least a week before this date to avoid losses. The first frost arrives around September 28 in the earliest one-in-ten years, so cover tomatoes and peppers from then.
How long is the growing season in Harwood Heights, IL?
The frost-free growing season in Harwood Heights is about 171 days. This window — from your last spring frost to your first fall frost — is when warm-season vegetables thrive. Cold-hardy crops like kale, spinach, and peas can extend your season by weeks on either side. In Harwood Heights (171 frost-free days, a moderate season), 30 of 56 planner crops fit outright, 25 get two plantings, 1 crop is perennial.
What USDA hardiness zone is Harwood Heights, IL?
Harwood Heights, IL is in USDA hardiness zone 6a (2023 USDA Plant Hardiness Zone Map). Zones come from the average coldest winter temperature, so they tell you which perennials survive the winter; the frost dates on this page tell you when to plant.
When should I start tomatoes indoors in Harwood Heights, IL?
Start tomatoes indoors Mar 21 and plant out May 9 in Harwood Heights. The planner uses the local median last frost and this crop's indoor-start and transplant offsets.
How many plantings of lettuce fit in Harwood Heights?
Two: plant Mar 28 and again by Aug 22; both mature before Oct 20.
When do I plant garlic in Harwood Heights?
Oct 13 to Nov 3; it overwinters and is ready the following summer.
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